CALPAIN-INDUCED LIGHT-SCATTERING BY CRYSTALLINS FROM 3 RODENT SPECIES

The purpose of the present investigation was to compare in vitro light scattering in the soluble proteins from rodent lenses after hydrolysi s by the calcium-activated protease, m-calpain (EC 3.4.22.17). Light s cattering was measured in solutions of lens proteins from mice, rats, and guinea pigs after activation of endogenous m-calpain or after addi tion of purified m-calpain. We found for the first time that, in addit ion to rat, crystallins from another rodent lens, young mouse, were su sceptible to calpain-induced light scattering. As in rats, aging of mo use lens prevented calpain-induced light scattering. Although crystall ins from guinea pig lens were also partially hydrolysed by calpain, ap preciable light scattering did not occur. Limited proteolysis may caus e common changes in the biophysical properties of mouse and rat crysta llins to decrease their solubility. Discovery of the nature of these b iophysical changes may help our understanding as to why crystallins pr ecipitate under cataractous conditions. (C) 1997 Academic Press Limite d.